MONTPELIER — With Vermont’s prison facilities aging, lawmakers are beginning to grapple with whether to build new or patch up the old.

The state Department of Buildings and General Services shared data with a legislative committee last week on the maintenance costs of all eight Vermont correctional facilities and the estimated cost of replacing them.

For example, the Chittenden Regional Correctional Facility faces nearly $11 million in deferred maintenance costs over the next 20 years. The estimated cost of replacing it would be about $28 million.

Officials say a problem is that some facilities, including Chittenden and the Marble Valley Regional Correctional Facility in Rutland, sit so tightly on their lots that they would be very difficult to expand.

Meanwhile, state officials say expansion may be needed to accommodate a corrections system that is trying to focus more on rehabilitating inmates than on warehousing them.

“It’s your buildings that will determine what kinds of policies Corrections can put in place,” said Rep. Alice Emmons, D-Springfield, chairwoman of the committee. “If you are really working to rehabilitate (offenders) and you need programming space, but the buildings are not designed to accommodate that, you can’t do it.”

Vermont’s state correctional facilities range in bed counts from 112 at the Caledonia Community Work Camp in St. Johnsbury to 420 at the Northern State Correctional Facility in Newport. Vermont also ships nearly 500 prisoners to private prisons in Kentucky and Arizona.

Deputy Corrections Commissioner Lisa Menard noted there has been interest among some lawmakers in recent years in trying to move the out-of-state inmates back to Vermont facilities.

Wanda Minoli, deputy commissioner at the buildings department, said 40 years is considered a good life span for a public building. Emmons said prisons “get really hard usage because of the population that’s housed there.”

The Chittenden facility dates to 1973 — 41 years ago — and has a proposed replacement date of 2015, which officials said won’t be met. The Northwest State Correctional Facility opened in 1969. The Southeast State Correctional Facility in Windsor dates to 1935, though it’s had several upgrades over the years.

While some of the prisons have little or no land left to expand, others are at or near capacity for their use of local water supplies and sewer systems.

Emmons said big building projects may be problematic given the state’s tight budget situation. Another committee of the Legislature approved a round of budget cuts, mainly for human services, a day before Thursday’s meeting of the corrections panel.

She noted that Vermont’s newest prison, the Southern State Correctional Facility in Springfield, which opened in 2003, was built with money from the state’s general fund. Most big building projects are paid for with borrowed money raised through the sale of bonds.